The research program described in this application is epidemiologic in design and approach. The primary purpose is to focus research activity in two areas of cancer epidemiology: malignancies of the hematopoietic system and the effects of ionizing and non-ionizing radiation exposures on the development of human cancer. Specifically, it is proposed that the following projects be continued and completed: 1) analyses from two population-based case-control studies of Hodgkin's disease directed at the identification of case aggregation and the development of a comprehensive model of risk; 2) the development of improved methods to detect and describe cancer case aggregation; 3) the application of such methodology to the study of case aggregation utilizing data from a study of acute nonlymphocytic leukemia; 4) an incidence study of pancreatic cancer among A-bomb survivors in Hiroshima and Nagasaki, Japan; 5) feasibility studies of potential health effects among persons exposed to radiation releases from the Hanford Nuclear Reservation; and 6) a population-based case-control study of female breast cancer in relation to residential exposure to electromagnetic fields and light at night. New research initiatives are proposed in the following areas: 1) further epidemiologic study of Hodgkin's disease; 2) a study of leukemia, by subtype, in relation to immune function, tobacco use, and case aggregation; 3) additional collaboration in the study of late radiation effects among A-bomb survivors; 4) studies of potential radiation effects surrounding the Hanford Nuclear Reservation; and 5) additional collaborative studies of the potential carcinogenic effects of power frequency electromagnetic fields. The RCDA would enhance my development as an independent investigator by providing stability in salary support and by substantially reducing my current teaching and administrative responsibilities. This would allow me to consolidate my activities and thereby devote approximately 90% of my time directly to the research priorities set forth in this application.